We are trying to combine two table instances as mentioned above, however both the instances might have same data in the specific field which is unique to its own data.However the data in the individual tables are necessarily different. On combining, the data might get over-written, which we do not want.

is it possble to append the data in the fields with a character before the data, so as to identify the table it comes from?

You have to first create the linked server for both these database and then can use JOIN statement to fetch the records.Please Vote & "Mark As Answer" if this post is helpful to you.
Cheers
Prakash Nandwana
Bangalore , India